Source/WTF/wtf/FixedVector.h

/*
 * Copyright (C) 2021 Apple Inc. All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
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 *    documentation and/or other materials provided with the distribution.
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#pragma once

#include <wtf/RefCountedArray.h>

namespace WTF {

// Wrapper around RefCountedArray, fixed-sized, memory compact Vector.
// Copy constructor / assignment operator work differently from RefCountedArray: works as like a Vector.
template<typename T>
class FixedVector {
public:
    using iterator = T*;
    using const_iterator = const T*;
    using reverse_iterator = std::reverse_iterator<iterator>;
    using const_reverse_iterator = std::reverse_iterator<const_iterator>;

    FixedVector() = default;
    FixedVector(const FixedVector& other)
        : m_storage(other.m_storage.clone())
    { }
    FixedVector(FixedVector&& other) = default;

    FixedVector& operator=(const FixedVector& other)
    {
        FixedVector tmp(other);
        swap(tmp);
        return *this;
    }

    FixedVector& operator=(FixedVector&& other)
    {
        FixedVector tmp(WTFMove(other));
        swap(tmp);
        return *this;
    }

    explicit FixedVector(size_t size)
        : m_storage(size)
    { }

    template<size_t inlineCapacity, typename OverflowHandler>
    explicit FixedVector(const Vector<T, inlineCapacity, OverflowHandler>& other)
        : m_storage(other)
    { }

    template<size_t inlineCapacity, typename OverflowHandler>
    FixedVector& operator=(const Vector<T, inlineCapacity, OverflowHandler>& other)
    {
        m_storage = other;
        return *this;
    }

    template<size_t inlineCapacity, typename OverflowHandler>
    explicit FixedVector(Vector<T, inlineCapacity, OverflowHandler>&& other)
        : m_storage(WTFMove(other))
    { }

    template<size_t inlineCapacity, typename OverflowHandler>
    FixedVector& operator=(Vector<T, inlineCapacity, OverflowHandler>&& other)
    {
        m_storage = WTFMove(other);
        return *this;
    }

    size_t size() const { return m_storage.size(); }
    bool isEmpty() const { return m_storage.isEmpty(); }
    size_t byteSize() const { return m_storage.byteSize(); }

    T* data() { return m_storage.data(); }
    iterator begin() { return m_storage.begin(); }
    iterator end() { return m_storage.end(); }

    const T* data() const { return const_cast<FixedVector*>(this)->data(); }
    const_iterator begin() const { return const_cast<FixedVector*>(this)->begin(); }
    const_iterator end() const { return const_cast<FixedVector*>(this)->end(); }

    reverse_iterator rbegin() { return m_storage.rbegin(); }
    reverse_iterator rend() { return m_storage.rend(); }
    const_reverse_iterator rbegin() const { return m_storage.rbegin(); }
    const_reverse_iterator rend() const { return m_storage.rend(); }

    T& at(size_t i) { return m_storage.at(i); }
    const T& at(size_t i) const { return m_storage.at(i); }

    T& operator[](size_t i) { return at(i); }
    const T& operator[](size_t i) const { return at(i); }

    T& first() { return (*this)[0]; }
    const T& first() const { return (*this)[0]; }
    T& last() { return (*this)[size() - 1]; }
    const T& last() const { return (*this)[size() - 1]; }

    void fill(const T& val) { m_storage.fill(val); }

    bool operator==(const FixedVector<T>& other) const { return m_storage == other.m_storage; }

    void swap(FixedVector<T>& other)
    {
        m_storage.swap(other.m_storage);
    }

    static ptrdiff_t offsetOfStorage() { return OBJECT_OFFSETOF(FixedVector, m_storage); }

private:
    friend class JSC::LLIntOffsetsExtractor;

    RefCountedArray<T> m_storage;
};
static_assert(sizeof(FixedVector<int>) == sizeof(int*));

template<typename T>
inline void swap(FixedVector<T>& a, FixedVector<T>& b)
{
    a.swap(b);
}

} // namespace WTF

using WTF::FixedVector;